"Unlikely" means that something has a low chance or probability of happening. It suggests that the possibility of it occurring is not very high. Full definition
It is a question that looks highly unlikely of coming to fruition, and I doubt if it would be supported by the fans either..... (justarsenal.com)
A similar situation seems unlikely in today's age of rock - bottom interest rates and easy money, but the company's history is worth being aware of. (simplysafedividends.com)
In the very very very unlikely event this turns out well.. (filmjunk.com)